HVAC Error Code H2 — What It Means & How to Fix It

What Does This Error Mean?

H2 means the compressor is drawing more electrical current than it should. The system detected this overcurrent condition and shut down to protect the compressor and electronics. Overcurrent can indicate a struggling compressor, a refrigerant problem, or an electrical fault. This is a critical error — do not keep restarting the system. Repeated starts under overcurrent conditions can permanently damage the compressor.

Affected Models

Mini-split air conditioners
Central air conditioners
Heat pump systems
Inverter and non-inverter split systems

Common Causes

The compressor is mechanically failing — worn bearings or seized pistons increase current draw significantly
Low refrigerant is causing the compressor to work harder, pulling more current than normal
Refrigerant overcharge creates excessive head pressure, making the compressor work against higher resistance
A failed run capacitor means the compressor cannot start efficiently and draws spike current at startup
A wiring fault or short circuit in the compressor circuit is causing abnormal current readings

How to Fix It

Shut the system off at the thermostat and cut power at the outdoor disconnect box. Allow the compressor at least 30 minutes to cool before any technician inspection.

A hot compressor running at overcurrent will reset its thermal protection and restart — only to hit the same fault again. Let it cool completely before troubleshooting.
Check the outdoor unit for restricted airflow. Blocked coils or poor clearance around the unit can cause high head pressure, which increases compressor current draw.

Remove any vegetation, debris, or objects within 18 inches of the unit. Clean visible debris from the coil surface with a garden hose (power off).
Do not attempt to open the outdoor unit or access the electrical components. The compressor circuit operates at high voltage and requires a licensed technician to work safely.

Testing compressor current draw requires an amp clamp meter and knowledge of the unit's rated full-load amperage. This is not a safe DIY measurement.
Note how old the system is. Compressors in systems over 10 years old are more prone to mechanical failure. Share the system age with the technician when you call.

An aging compressor may still be repairable if caught early. However, if the compressor is near end of life, it may be more cost-effective to replace the entire outdoor unit.
Call an HVAC technician and describe the H2 error and any symptoms you noticed — such as unusual noise, reduced cooling, or tripped circuit breakers.

A clicking or humming sound when the system tries to start often points to a failed capacitor. This is a relatively inexpensive repair if caught before the compressor burns out.

When to Call a Professional

H2 is a critical fault — stop using the system and call an HVAC technician immediately. A compressor drawing too much current is at serious risk of burning out its windings. Burned compressor windings mean a full compressor replacement costing $1,000 to $3,000. A technician can catch this early with an amp clamp meter and prevent total failure. Prompt diagnosis can be the difference between a $200 fix and a $2,000 repair.

Frequently Asked Questions

What causes a compressor to suddenly draw too much current?

There are several common causes. A failing run capacitor is the most frequent culprit — the capacitor helps the compressor start smoothly. Without a working capacitor, the compressor struggles to start and draws several times its normal current. Low refrigerant, dirty coils, or a mechanically failing compressor can also cause sustained overcurrent.

My circuit breaker tripped at the same time as H2 appeared. Are they related?

Yes — when the compressor draws too much current, it can trip the circuit breaker at the electrical panel. This is actually the breaker doing its job — protecting the wiring from overheating. If your breaker trips repeatedly when the system tries to start, that is a classic sign of compressor or capacitor problems. Do not keep resetting the breaker — call a technician.

How long do HVAC compressors typically last?

A well-maintained compressor typically lasts 10 to 15 years. Systems that run with low refrigerant, dirty coils, or poor electrical supply tend to fail sooner. Regular annual maintenance — including checking refrigerant charge and cleaning coils — significantly extends compressor life. If your system is approaching 12 to 15 years, an H2 fault may signal that it is nearing end of life.